Two clones for structural genes coding for proteins secreted from the rat ventral prostate have been identified by hybrid arrest translation. The two cloned structural genes are currently being mapped with a variety of restriction endonucleases. Restricted recombinant plasmid is being electrophoresed on agarose gels and prostate insert fragments are isolated. The prostate inserts will be used for preparing radioactive probes which will be nick translationed and used to screen a chromosomal rat gene library carried in lambda phage charon 4A. Similar protocols will be followed after isolation and identification of the human prostate structural gene for the major secretory protein (17,000 daltons) from human prostate.